Fiber optic switches are known for the control of such things as a wall receptacle and an electrical circuit. U.S. Pat. No. 4,704,656 issued Nov. 3, 1987 to Neiger discloses an optical fiber interconnection between a switch and a load such as an electrical wall receptacle. Light at a load end is transmitted along a single fiber to a switch consisting of a pivotal mirror. In a reflecting position the mirror reflects light back down the fiber and onto a photoresistor to cause the actuation of a relay. A major problem with the Neiger arrangement is the criticality of alignment of the mirror used to reflect the light. Utilizing the mirror reflector whose alignment is critical as a pivotal switch creates a severe potential misalignment source. Also, the mirror restricts the invention to "single throw" switch configuration precluding its use for colour multiplexing which involves the simultaneous transmittal of data using selected colours or wavelengths.
A simple switch which switches the light travelling along the fiber itself is disclosed in Applicant's application filed in the United States on Sep. 6, 1989. The latter switch utilizes one fiber for input and another for the output when switching from ON to OFF or, when switching between two different outputs, two separate output fibers. Clearly, in any application a reduction in the number of fibers will produce a corresponding increase in reliability and reduction in system cost. Consequently, any further simplification of the basic switch invention described in the above-referenced U.S. patent application which results in a reduction particularly in the number of fibers would likely result in a significant increase in reliability.
Accordingly, it is an object of the invention to provide an improved fiber optic switch. It is a further object of the invention to provide a fiber optic switch which utilizes a single optical fiber path means between the switch and the element detecting the switch position. It is yet a further object to provide a fiber optic switch which is substantially less susceptible to misalignment than previously known single fiber systems. It is yet a further object of the invention to have an optical geometry that is simple to manufacture and insensitive to reasonable manufacturing tolerances. Yet a further object is to provide means for combining a plurality of switches and switch position detectors using a single fiber.